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Basics ⬇

Author(s): AliciaChitanand, DO and Kenneth P.Barnes, MD, MSc, CAQSM, FACSM

Description

  • Accessory navicular: unfused accessory ossification center at posterior tibialis tendon (PTT) insertion
  • Geist classification:
    • Type I: small sesamoid bone in PTT (usually 2 to 3 mm)
    • Type II: synchondrosis between navicular and os naviculare (usually 8 to 12 mm triangular or heart shaped); 70% of symptomatic lesions
    • Type III: cornuate navicular (questionable end stage of type II with ossification across synchondrosis)
  • Synonym(s): os tibiale (externum); os naviculare (secundarium); symptomatic accessory tarsal navicular; accessory scaphoid bone; accessory tarsal scaphoid; navicular secundum; prehallux; os scaphoideum accessorium
  • Osteonecrosis of tarsal navicular in adults: Mueller-Weiss disease
ALERT

  • Köhler disease: articular osteochondrosis with secondary involvement of articular and epiphyseal cartilage as a consequence of avascular necrosis of tarsal navicular bone; synonyms: aseptic necrosis of tarsal navicular; avascular necrosis of navicular; Koehler disease; idiopathic osteonecrosis of navicular in children
  • Iselin disease: nonarticular osteochondrosis of the 5th metatarsal at site of ligament and tendon attachment and trauma; synonym: traction apophysitis of 5th metatarsal where peroneus brevis inserts

Epidemiology

  • Accessory navicular:
    • Most often symptoms found in active children and females in 4th decade
    • Second most common accessory bone of foot
    • Accessory bones in 36% of asymptomatic feet
  • Iselin disease:
    • Usually in athletic older children and adolescents (1)
ALERT

  • Köhler disease: rare:
    • Age of onset 2 to 9 yr
    • Mean age of diagnosis: males 6 yr, females 4.5 yr
  • Occasionally bilateral Iselin disease: rarely reported but probably more common than appreciated:
    • Age of onset in late childhood or early adolescence
    • Apophysis appears: males 8 to 11 yr, females 11 to 14 yr
    • Apophysis fuses about 2 yr later.

Prevalence

  • Accessory navicular:
    • 4–21% of general population: most asymptomatic
    • 50–90% bilateral
    • In skeletally immature, 64% symptomatic
  • Köhler disease: prevalence unknown
  • Iselin disease: prevalence unknown

Etiology and Pathophysiology

  • Accessory navicular: becomes symptomatic in the following:
    • Adolescent patients from chondroosseous disruption owing to tension and shear forces from PTT and foot dynamics (type II)
    • From pressure of overlying footwear (all types)
    • Older patients owing to posttraumatic disruption of synchondrosis (type II) ± PTT avulsion or rupture
    • Symptomatic type II: microfracture, acute and chronic inflammation, and cellular proliferation
  • Köhler disease:
    • Tarsal navicular is last bone to ossify and believed to be more susceptible to compression injury.
    • May be due to ischemia from recurrent cumulative microtrauma or acute macrotrauma
  • Iselin disease:
    • Repetitive traction from peroneus brevis
    • Acute avulsion fracture with widening of chondroosseous junction

Risk-Factors

  • Accessory navicular: may be worse with hyperpronation
  • Köhler disease: may be more common in late ossification of tarsal navicular
  • Iselin disease:
    • May be more common with tight calf muscles
    • Seen most commonly in soccer, basketball, gymnastics, and dance

Commonly Associated Conditions

Köhler disease: occasionally with other osteochondroses, such as Osgood-Schlatter or Legg-Calvé-Perthes disease

Diagnosis ⬆ ⬇

  • Accessory navicular:
    • Symptomatic or asymptomatic
    • Most often clinically relevant accessory navicular is symptomatic type II.
  • Köhler disease:
    • Based on history and x-ray findings
    • Does not equal asymptomatic feet with abnormal x-ray findings: multiple ossification centers or other process
  • Iselin disease: based on history and x-ray findings

History

  • Accessory navicular:
    • Asymptomatic or medial foot pain with navicular bump
    • If painful, onset gradual or acute
    • If painful, onset may be secondary to ankle sprain or contusion.
    • Worse with activity (during or after) and compression with shoes
    • May have limp/antalgic gait
  • Köhler disease:
    • Medial foot pain (tenderness at tarsal navicular)
    • Usual gradual in onset
    • Worse with activity
    • Limp/antalgic gait
  • Iselin disease:
    • Lateral foot pain (tenderness at proximal 5th metatarsal)
    • Usual insidious onset
    • May be acute after significant trauma; often inversion injury
    • Worse with weight-bearing, lateral movements, cutting, and jumping
    • Limp/antalgic gait

Physical Exam

  • Accessory navicular:
    • Protuberant tarsal navicular (posteromedial aspect)
    • Normal range of motion (ROM) of foot, ankle, hindfoot
    • Possible overlying swelling
    • Tender to palpation over tarsal navicular ± PTT distally
    • Pain with resisted plantar flexion and inversion
  • Köhler disease:
    • Antalgic gait with shifting of weight to lateral aspect of foot
    • Possible overlying swelling
    • Less likely overlying warmth
    • Tender to palpation over tarsal navicular
    • May have pain with resisted plantar flexion and inversion
  • Iselin disease:
    • Perhaps prominent proximal 5th metatarsal
    • Very little or no erythema, edema, or ecchymosis
    • May show mild pronation
    • Tender to palpation at peroneus brevis insertion
    • Pain with resisted eversion, extreme inversion, and extreme plantar flexion or dorsiflexion

Differential Diagnosis

  • Accessory navicular:
    • Navicular pathology (stress fracture, tuberosity avulsion fracture)
    • PTT pathology (tendinopathy, tenosynovitis, rupture, dysfunction)
    • Less commonly: deltoid/spring ligament injury, tarsal tunnel syndrome, Köhler disease (in younger patients), tarsal coalition, plantar fasciitis, tight heel cord
    • Systemic: infection, malignancy
  • Köhler disease:
    • Accessory navicular, trauma, stress fracture, infection, malignancy
    • If not better with conservative treatment, rarely tarsal coalition (congenital or acquired)
  • Iselin disease:
    • Fractures: 5th metatarsal (acute Jones and stress more transverse line), avulsion fracture (more common with lateral ankle sprains and more oblique line)
    • Os vesalianum (incidence 0.1–1%; most often asymptomatic; found within peroneus brevis tendon)

Diagnostic Tests & Interpretation

  • Accessory navicular:
    • Radiographs:
      • Anteroposterior and lateral foot often miss.
      • Must include external oblique view
      • Findings depend on type (see “Geist classification” in “Description”).
    • Ultrasound (US):
      • More for tendinous abnormalities
      • May see heterogeneous synchondrosis (compared with asymptomatic side)
      • May see diastasis in older patient
    • Magnetic resonance imaging (MRI):
      • Rarely needed
      • Short tau inversion recovery (STIR) images show increased signal within accessory navicular at PTT insertion.
    • Bone scan:
      • Increased uptake in region
      • Only 50% specific but 100% sensitive (2)[B]
  • Köhler disease:
    • Radiographs:
      • Anteroposterior and lateral foot
      • Commonly, narrowing/flattening of the tarsal navicular and/or loss of trabecular pattern
      • Possibly, apparent fragmentation or diffusely increased density in normal-shaped tarsal navicular
      • Do not confuse with multiple ossification centers without increased density.
    • Bone scan:
      • Decreased uptake, or “cold area”
      • May be present before x-ray changes (3)
    • MRI:
      • Rarely needed
      • Low signal on T1 and high signal on T2
  • Iselin disease:
    • Radiographs:
      • Anteroposterior and lateral foot often miss diagnosis.
      • Must include medial oblique view
      • Consider comparing with unaffected side.
      • Apophyseal widening and often fragmentation of ossification center
      • Found almost parallel to long axis of shaft
      • Occasionally, with cystic changes of physis
  • Pathologic findings:
    • Accessory navicular: histologically, microfracture, acute and chronic inflammation, and cellular proliferation in symptomatic lesions

Treatment ⬆ ⬇

General Measures

  • Accessory navicular:
    • Rest, shoe insert/orthotic (soft orthotic initially until pain free and then assess mechanics to see if semirigid orthotic is better for longer term support)
    • Application of doughnut pad over bony prominence
    • Analgesics
    • Physical therapy
    • Occasionally, cast immobilization is warranted.
  • Köhler disease:
    • If mild disease, soft arch supports only
    • Short leg cast (10 to 15 degrees of varus, 10 to 20 degrees of equinovarus) for 6 to 8 wk followed by arch support if mild pain persists
    • Casting may lead to shorter length of pain.
    • No significant difference in final outcome between short leg cast and shoe correction, rest, or non–weight-bearing with crutches (4,5)[C]
    • Symptom duration: 8+ wk of casting: 2.5 mo; <8 wk of casting: 4 mo; noncasting: 15.2 mo (5)[C]
  • Iselin disease:
    • Rest, ice, calf stretching
    • If severe pain, immobilization for 2 to 4 wk (Aircast, walking cast, or short leg cast with crutches)
    • Physical therapy to improve strength and coordination when pain free

Medication

Analgesics (e.g., acetaminophen and nonsteroidal anti-inflammatory drugs [NSAIDs]) for pain

Surgery/Other Procedures

  • Accessory navicular:
    • Indication: no improvement with nonoperative treatment
    • Resection of symptomatic bone with Kidner procedure ± reattachment of PTT (6)[C]
    • Possible percutaneous drilling in young athletes (7)[C]
    • Fixation by screw or tension band wiring has shown improved pain and function (8)[A].
  • Iselin disease:
    • Indication: failure of conservative treatment and symptomatic nonunion
    • Very rarely indicated
    • Resection or fixation of symptomatic bone (9)[C]

Ongoing Care ⬆ ⬇

Prognosis

  • Accessory navicular:
    • Most do not become painful.
    • Painful lesions in adolescents often improve with growth.
    • Uncertain prognosis for symptomatic lesion treated nonoperatively
    • Continued symptoms more likely with recurrent stresses of athletics
    • Anecdotally, less likely to improve in physically active youth owing to repeated injury
    • Uncertain if bony union is natural course (10–50% fusion reported)
  • Köhler disease:
    • Self-limiting and excellent prognosis
    • Full reconstitution of tarsal navicular (6 to 13 mo, average 8 mo) (4)[C]
    • No evidence of arthritis long term (4,5)[C]
    • Potentially, minor faceting of tarsal navicular (5)[C]
  • Iselin disease:
    • Pain resolves with relative rest, immobilization, or eventual bony union.
    • Rare reports of nonunion and prolonged symptoms

Additional Reading ⬆ ⬇

  • Canale ST, Williams KD. Iselin’s disease. J Pediatr Orthop. 1992;12(1):90–93.
  • Keles-Celik N, Kose O, Sekerci R, et al. Accessory ossicles of the foot and ankle: disorders and a review of the literature. Cureus. 2017;9(11):e1881.
  • Sella EJ, Lawson JP, Ogden JA. The accessory navicular synchondrosis. Clin Orthop Relat Res. 1986;(209):280–285.
  • Ugolini PA, Raikin SM. The accessory navicular. Foot Ankle Clin. 2004;9(1):165–180.

References ⬆ ⬇

  1. Forrester RA, Eyre-Brook AI, Mannan K. Iselin’s disease: a systematic review. J Foot Ankle Surg. 2017;56(5):1065–1069.
  2. Chiu NT, Jou IM, Lee BF, et al. Symptomatic and asymptomatic accessory navicular bones: findings of Tc-99m MDP bone scintigraphy. Clin Radiol. 2000;55(5):353–355.
  3. Khoury J, Jerushalmi J, Loberant N, et al. Kohler disease: diagnoses and assessment by bone scintigraphy. Clin Nucl Med. 2007;32(3):179–181.
  4. Ippolito E, Ricciardi Pollini PT, Falez’ F. Köhler’s disease of the tarsal navicular: long-term follow-up of 12 cases. J Pediatr Orthop. 1984;4(4):416–417.
  5. Williams GA, Cowell HR. Köhler’s disease of the tarsal navicular. Clin Orthop Relat Res. 1981;(158):53–58.
  6. Ray S, Goldberg VM. Surgical treatment of the accessory navicular. Clin Orthop Relat Res. 1983;(177):61–66.
  7. Nakayama S, Sugimoto K, Takakura Y, et al. Percutaneous drilling of symptomatic accessory navicular in young athletes. Am J Sports Med. 2005;33(4):531–535.
  8. Jang HS, Park KH, Park HW. Comparison of outcomes of osteosynthesis in type II accessory navicular by variable fixation methods. Foot Ankle Surg. 2017;23(4):243–249.
  9. Ralph BG, Barrett J, Kenyhercz C, et al. Iselin’s disease: a case presentation of nonunion and review of the differential diagnosis. J Foot Ankle Surg. 1999;38(6):409–416.

Clinical Pearls ⬆

  • Symptomatic type II accessory navicular may respond less favorably to conservative treatment in adolescent athletes.
  • Asymptomatic radiologic abnormalities without pain or antalgic gait are not Köhler disease.
  • Avascular necrosis of the tarsal navicular in an adolescent or an adult is not Köhler disease.
  • Iselin disease is probably missed often but has a good prognosis.